Mobile communication apparatus

Abstract

Mobile communication apparatus, of small size and low cost, may be installed in vehicles to afford enhanced mobile-to-mobile communications between preceding and succeeding vehicles, even over a great distance therebetween. In the preceding vehicle, a detector detects a carrier transmitted from the succeeding vehicle and a transmission controller uses the carrier, when detected, for transmitting data to the succeeding vehicle. Further, the detector in the preceding vehicle detects, from the carrier transmitted from the succeeding vehicle, whether the distance to the succeeding vehicle is in a range permitting two-way communications therebetween. The transmission controller in the preceding vehicle transmits first information to the succeeding vehicle when the detector does not detect the possibility of two-way communication, and transmits second information to the succeeding vehicle when the detector detects the possibility of two-way communications with the succeeding vehicle.

1. A mobile communications system providing, selectively, one-way and two-way communications between a preceding road vehicle and a succeeding road vehicle, comprising:
 in the succeeding road vehicle:
 a receiver receiving a carrier signal from the preceding road vehicle, 
 a detector detecting whether a signal level of the carrier signal received from the preceding road vehicle is above a predetermined signal level and producing a corresponding detection output, and 
 a communications controller, in response to the detection output of the detector, transmitting information on a modulated carrier signal to the preceding road vehicle; and 
 
 in the preceding road vehicle:
 a detector detecting a carrier signal transmitted from the succeeding road vehicle and received by the preceding road vehicle and determining if communication is possible for the received and detected carrier signal and, if so, producing a corresponding carrier signal detection output, and 
 a communications controller, in the absence of a carrier signal detection output from the detector indicating a detector determination that communication on the carrier is not possible, transmitting data to the succeeding terrestrial vehicle by one-way communication and, in response to the carrier signal detection output of the detector indicating a detector determination that communication on the carrier is possible, performing two-way communications between the succeeding and preceding terrestrial vehicles. 
 
 
   
   
     2. The mobile communication apparatus claimed in  claim 1 , wherein:
 the detector produces a carrier detection output indicating a detector determination that communication on the carrier is possible, in response to continuous detection of the carrier signal thereby for at least a fixed period of time. 
 
   
   
     3. The mobile communication apparatus as claimed in  claim 1 , wherein:
 the detector produces a carrier detection output indicating a detector determination that communication on the carrier is possible, when the signal level of the received carrier exceeds a predetermined level. 
 
   
   
     4. The mobile communications system of  claim 1 , wherein:
 information transmitted by the two-way communication has a higher accuracy than information transmitted by the one-way communication. 
 
   
   
     5. The mobile communications system of  claim 1 , wherein:
 a continuous transmission frequency of the two-way communication is higher than the continuous transmission frequency of the one-way communication. 
 
   
   
     6. The mobile communications system of  claim 1 , further comprising:
 a discriminator determining a distance between the preceding and succeeding road vehicles as a function of the detected signal level of the carrier signal. 
 
   
   
     7. The mobile communications system of  claim 1 , further comprising:
 a radar system detecting a predetermined distance between the preceding and succeeding road vehicles and producing a corresponding detection output enabling the two-way communications. 
 
   
   
     8. A mobile communications system as recited in  claim 1 , wherein:
 in each of the succeeding and preceding road vehicles, in response to the corresponding detection outputs of the respective detectors indicating detector determinations that communication on the respective carriers is possible, the respective communications controllers perform two-way communications between the succeeding and preceding road vehicles. 
 
   
   
     9. The mobile communication apparatus claimed in  claim 8 , wherein:
 the detector produces a carrier detection output in response to continuous detection of the carrier signal thereby for at least a fixed period of time. 
 
   
   
     10. The mobile communication apparatus as claimed in  claim 8 , wherein:
 the detector produces a carrier detection output when the signal level of the received carrier exceeds a predetermined level. 
 
   
   
     11. The mobile communications system of  claim 1 , further comprising:
 said communication controller in the preceding road vehicle transmits information indicating the operational status of the driver of the preceding road vehicle. 
 
   
   
     12. A mobile communications system providing, selectively, one-way and two-way communications between a preceding road vehicle and a succeeding road vehicle and comprising, in at least one of the succeeding and preceding road vehicles:
 a detector detecting whether a condition for two-way communications between the preceding and succeeding road vehicles is satisfied, and producing a corresponding detection output; and 
 a communications controller, in the absence of a carrier signal detection output from the detector, transmitting data to the other of the succeeding and preceding road vehicles by a one-way communication and, in response to the carrier signal detection output of the detector, transmitting data in two-way communications to and from the other of the succeeding and preceding road vehicles. 
 
   
   
     13. The mobile communications system of  claim 12 , wherein:
 information transmitted by the two-way communication has a higher accuracy than information transmitted by the one-way communication. 
 
   
   
     14. The mobile communications system of  claim 12 , wherein:
 a continuous transmission frequency of the two-way communication is higher than the continuous transmission frequency of the one-way communication. 
 
   
   
     15. The mobile communications system of  claim 12 , wherein the detector comprises:
 a discriminator determining a distance between the preceding and succeeding road vehicles as a function of the detected signal level of the carrier signal. 
 
   
   
     16. The mobile communications system of  claim 12 , further comprising:
 a radar system detecting a predetermined distance between the preceding and succeeding road vehicles and producing a corresponding detection output enabling the two-way communications.